Multilayer metal foil insulation has been used for many years, as illustrated by U.S. Pat. No. 1,934,174. Such metal foil insulation has typically been used in high temperature applications for reflective heat insulation. In those applications, the layers of metal foils are embossed to provide separation between the layers, and the stack of layers are protected in a container or rigid cover to prevent the stack of metal foils from becoming compressed at any portion, which would decrease the heat insulation value of the stack.
U.S. Pat. No. 4,251,598 discloses a reflective insulative panel having numerous layers such as an outer facing sheet encapsulating numerous cellular foil sheets. The layers are made from aluminum or stainless steel and are preformed with triangular-shaped ribs extending at right angles to each other throughout the length of the material and when stacked form closed cells that trap air to prevent heat loss due to convection.
U.S. Pat. No. 5,011,743 discloses that multilayer metal foil insulation can provide enhanced performance as a heat shield when a portion of the multilayer metal foil is compressed to provide a heat sink area through which heat is collected from the insulating portions of the stack and dissipated from the heat shield. Such multilayer metal foil heat shields are formed from a stack of embossed metal foil layers by compressing portions of the stack to create the desired heat sink areas. The layers are attached to each other or stapled together to prevent the layers from separating.
U.S. Pat. No. 5,763,857 discloses a heating appliance with a metal foil insulating jacket comprising air tight chambers.
U.S. Pat. No. 6,586,111discloses multilayer metal foil insulating panels having a layered structures of at least two corrugated metal layers separated by an intermediate layer of a non-corrugated, generally flat metal foil layer.
U.S. Patent Publication No. 2002/0098316 A1 discloses a multilayer foil insulating structure for dissipating heat and attenuating sound. In one embodiment, a retainer layer composed of expanded metal sheet stock 0.050 inches thick is used to form an insulation structure with other foil layers. Apertures in the expanded metal sheet allow for the passage of sound and air.